Are the differences between hardware just affecting graphic quality only?

I mean, okay, BluRay discs can hold a LOT more info in one go, which means it should be able to hold a lot more information uncompressed (textures, sound clips, etc) which should translate into better loading speeds.

Note that the above paragraph is just a theory. I don't know whether it works out like that in real life.

What other differences are there from a technical standpoint?